1. Field of the Invention
This invention is in the field of cyclone heat exchangers, particularly those employed for direct heat exchange between a granular product and hot exhaust gases in the manufacture of cement. The invention is particularly concerned with an immersion pipe which extends through the cover of the cyclone heat exchanger and is composed of a plurality of loosely fitting segments extending in the longitudinal direction of the immersion pipe, the segments being releasably secured to the cover.
2. Description of the Prior Art
In German Pat. No. 23 61 995 there is described a cyclone heat exchanger having an immersion pipe centrally projecting into the heat exchanger from the top and being rigidly connected to the cover of the cyclone heat exchanger. In its central area this single-piece immersion pipe is provided with gas entry openings in its pipe jacket, the openings being formed by means of radial impression of brackets.
Cyclone heat exchangers having a sigle-piece immersion pipe rigidly connected to the cover, particularly when used for direct heat exchange between a granular product and hot kiln exhaust gases in the pre-calcining stage of a rotary tubular kiln system for manufacturing cement, are subject to bending and battering. As a result, cross-sectional changes of the immersion pipe can occur due to high thermal overloads particularly in the radial direction and often local in scope. The danger also exists that the immersion pipe will break in the area of the rigid connection to the heat exchanger or that parts will separate from the immersion pipe jacket and fall into the heat exchanger. This danger particularly exists in cyclone heat exchangers which must be dimensioned in large sizes for high throughput and separating efficiency and particularly those which directly follow the rotary tubular kiln and/or are equipped with auxiliary heating units such as a "Pyroclon" unit.
A change in the cross section of the immersion pipe not only leads to a considerable diminution of the separating efficiency but also can lead to a change in the flow resistance of the gas in the pre-calcining zone which provides a disadvantageous effect on the overall calcining process. If the immersion breaks off or parts thereof break off and fall into the cyclone heat exchanger, a blockage of the cyclone discharge can occur so that the entire rotary tubular kiln heat exchanger system must be shut down. The loss of production and very high repair costs are the natural consequence.